ZIF-8 micromembranes for gas separation prepared on laser-perforated brass supports

Abstract

ZIF-8 is an imidazolate-based metal–organic framework (MOF). ZIF-8 micromembranes of 20–32 μm diameter are prepared by synthesizing the MOF on Nd:YAG laser-perforated 75 μm thick brass sheets (63/37 Cu/Zn). The laser irradiation activates the brass support, promoting ZIF-8 growth. A thick and continuous ZIF-8 membrane is crystallized on the laser irradiation outlet side of the support, while the inlet side and the inner surface of the microperforations are also coated with ZIF-8 intergrowth crystals. Laser perforated brass supports are not only cheap, flexible, strong, and easy to handle and to process as membrane materials; they are also chemically compatible with the ZIF-8 composition because of the shared Zn element. The ZIF-8 membranes obtained are characterized by XRD, SEM, EDX, TGA and N₂ sorption analysis. Furthermore, the membranes are applied to the separation of equimolar H₂–CH₄, He–CH₄, CO₂–CH₄ and O₂–N₂ mixtures confirming the expected molecular sieving effect due to the MOF microporosity.